The homeworld ship for the Retahna fleet.
Later, Altarrion would interface with the ship and become it’s core AI, effectively making the ship his body.
The Astrum Domus would come to rest on Titan, Saturn’s moon, and be the home of the Retahna for the 2000 years after the end of season 3. Altarrion continues to await the galactic shunt that occurred at the end of the third season so that he can move the Retahna away from Titan and help preserve humanity from any threat possible.
It’s unknown what condition the Retahna are in after this long period on Titan…